<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #wrap::after {
            content: '';
            display: block;
            width: 200px;
            height: 200px;
            background: pink;
        }
        #wrap::first-letter {
            color: red;
            font-size: 24px;
            font-weight: bold;
        }
        /*:first-line*/
        #wrap::selection {
            background: #07daa5;
            color: #fff;
        }
        :root {
            border: 1px solid;
        }
    </style>
</head>
<body>
    <div id="wrap">
        伪类伪元素
    </div>
</body>
</html>
